It is known to provide a gaming system which comprises a game controller arranged to randomly display several symbols from a predetermined set of symbols and to determine a game outcome such as a game win based on the displayed symbols. Such gaming systems may commonly be implemented as a stepping machine provided with reels with each reel carrying several symbols of the set, or a video machine wherein selected symbols are displayed on virtual reels on a graphical display device. Win outcomes can occur based on symbols appearing in one or more horizontal lines, diagonal lines, or any other predetermined way.
It is also known to award high paying prizes, referred to as jackpot prizes, which may be funded from a prize pool. Typically, a portion of a gaming machine's turnover is forwarded to a jackpot prize controller which maintains the prize pool. One common way of awarding a jackpot prize is based on achieving a certain symbol or symbol combination in the game, often referred to as a symbol driven jackpot. However, a problem with this sort of jackpot awarding technique is that the probability of being awarded the jackpot prize (or simply qualifying for the prize) is not tied to the amount wagered in the game and thus does not meet regulatory gaming requirements for many jurisdictions. To overcome this problem, some gaming systems have been modified so as to increase the number of jackpot trigger symbols available for selection in the game, as the wagered amount is increased. However, such modification does not result in any visual enhancement to the player and is not always possible to implement, particularly for games having fixed symbol carriers such as the aforementioned stepper reel gaming machines.